simonite

Etymology
Simonite (TlHgAs 3 S 6 ), found in Allchar, Macedonia, Yugoslavia, named in 1982 for Simon Engel, son of Peter Engel (b. 1942), a Swiss crystallographer, +

Noun

 * 1)  A monoclinic-prismatic red mineral containing arsenic, mercury, sulphur, and thallium.